Onychomycoses represent a group of nail affections caused by one or more fungi. Whether aging represents a risk factor for developing onychomycosis, remains a question. In the present work, we studied the variations in frequency and prevalence of onychomycoses and non-mycotic onychodystrophies according to age. Our results show that there is an increase in the frequency and prevalence of onychomycoses and non-mycotic onychodystrophies predominantly in patients over forty years of age. ©2005 Revista Iberoamericana de Micología.